In many places, while supermarkets are free to fill the streets with cars and cover the ground with asphalt, the customers of small shops pay high prices for on-street parking: in England this is about the only discretionary revenue source for local governments, with predictable results – in my neighborhood, Harringay, in London, a non-resident on-street space is priced at £3 (about $4.80) per hour, 9.5 hours per day, 6 days per week. Allowing for holidays, and assuming full occupancy but ignoring additional charges (fines) for over-staying, this works out to £8,607 ($13,771) per year.
That versus the plan that’s just died in Massachusetts, which might have taxed parking lots with twenty or more spaces at $2 per space per day. A proposal in another borough of London to tax supermarket spaces at a modest rate of £600 (about $900) per year was met by screeds like this and never enacted. Campaigns to save small shops get loudendorsements, but the free ride for supermarket parking is seldom mentioned.

If you think for a moment about the massive external costs of urban road traffic (local air pollution, carbon in the atmosphere, roads unsafe for children or pedestrians & cyclists generally, buses stuck in traffic); the heavy environmental costs of the impermeable surfaces of parking lots themselves; the massive amounts of cement that go into (and thus carbon produced by) the erection of parking structures … taxing retail and commuter parking is a no-brainer.